Electronic security systems have been increasingly employed in recent years to protect building structures from intrusion, vandalism, and theft of contents. Some conventional security systems are based on a secured perimeter, which when breached activates an audio alarm and/or sends a signal to a security monitoring firm or the police. Other conventional systems utilize commercially available motion detectors to monitor for movement within the secured building. Detection of motion results in the sounding of an alarm.
Examples of motion detector-based security systems for building structure protection are disclosed in U.S. Pat. Nos. 4,288,867 to Guthard, which discloses a security system utilizing an ultrasonic motion detector, and 4,857,912 to Everett, Jr., et al., which discloses a multisensor security system including ultrasonic, optical, microwave, infrared, and video motion detectors.
A further example of a conventional building structure security system is disclosed by U.S. Pat. No. 4,642,612 to Crump, which discloses an interior security system that may include motion detectors mounted to monitor the exterior of a house. This system includes both audio alarms and an automatic phone dialer that are activated in response to detected intrusion. Such conventional security systems are typically designed for indoor use.
Another type of conventional security system is disclosed by U.S. Pat. No. 4,602,357 to Yang et al. The system includes multiple miniature portable transmitters that can be triggered to produce a coded ultrasonic or audio signal. The signals are received by correspondingly coded receivers that communicate via hard wire, a telephone link or wireless radio with a central processing unit. The transmitters may include accelerometers to detect movement of property with which they are associated, and may be used externally, such as in parking lots. However, such transmitters need to be mounted directly on the property being protected. In addition, the disclosed system includes many separate components, and thus is difficult to set up and maintain.
Convenient electronic security systems for monitoring exterior sites, such as construction zones and pools, have not been available. Likewise, security systems for protecting outdoor property, such as automobiles and boats, are not available, except for dedicated security systems that are mounted within or directly on the vehicle. This is particularly true when the site or property to be protected is not surrounded by a perimeter, such as a fence, breaches in which could be monitored in order to detect intrusion.
Another problem associated with conventional security systems based on motion detectors is the likelihood of false alarms. While security systems generally are intended to detect human intrusion, they are also activated by any other detected motion, including intruding pets or naturally occurring falling objects. Such problems would be compounded in any system expected to monitor an external site, because of the greater likelihood of animal intrusion, including cats, dogs, birds, rodents, and other creatures.
U.S. Pat. No. 5,214,411 to Herbruck discloses an animal repelling device including a battery power pack and an ultrasonic emitter. The emitter is adjustable and positioned relative to the housing to create different patterns of ultrasonic monitoring. An infrared detector integrated within the housing detects animal motion and then activates an ultrasonic emitter to drive the animal away. However, this system is primarily intended to repel animals to prevent soiling of the user's property. The system does not include any hardware for activating an alarm audible to humans or any other type of alarm device intended to repel humans or call aid to deal with the intrusion.
U.S. Pat. No. 4,658,386 to Morris discloses a lid for a garbage can that is outfitted with an infrared detector and an ultrasonic sound generator to repel animals. Again, no provision to repel intruders exists.
There thus exists a need for an integrated, portable security system for use in monitoring exterior sites that is not prone to frequent false alarms.